IMPLICATION OF LANDSAT IMAGES ON VERIFICATION OF DEEP-SEATED TRANSVERSE FAULTS IN SE ZAGROS FOLD-THRUST BELT, IRAN

Zagros fold-thrust belt is a foreland portion of Zagroside orogeny in SW Iran, resulted from Alpine type continental collision between Arabia and Eurasia during Mesozoic and Cenozoic. The belt itself, lies on the northeast margin of the Precambrian (Pan African) basement, contains huge and elongated box-shaped anticlines penetrated by salt plugs. The anticlines, in kinematics, are dominantly thrust related and are trending generally NW-SE in Lorestan and Fars but change to E-W in Larestan and finally to NE-SW trend close to Oman syntaxis. The Larestan portion of the belt, located in transitional zone, was chosen to investigate in more detail the geometry and style of the structures using Landsat TM images in different scales.

Topography, drainage pattern, rock spectral reflection, curvilinear geometry of fold hinges, and geometry of younger fold hinges have been utilized to document and map the transverse lineaments. Up on these criteria, two different subsurface strike-lateral transverse fault sets have been identified. The first set, trending NE-SW was documented based on left lateral displacement of the foreland structures, on alignment of salt plugs pierced anticline hinge zones, and on left lateral curvilinear geometry of the fold hinges. The second sets, trending NW-SE, however, have not touch the surface, therefore no alignment of salt plugs and surface displacement of the structures seen along it. Nevertheless, determination of right lateral curvilinear geometry of the foreland fold hinges and generation of younger folds detected their right lateral movement.

Emplacement of Precambrian salt plugs to surface by movement of right-lateral transverse faults cut anticlines cored the plugs, and curvilinear geometry and displacement of the foreland fold hinges along the subsurface lineaments implies that these lineaments are deep-seated. Trends of these deep-seated transverse faults can be correlated by trend of basement faults in northern margin of Arabian platform. Accordingly, it is proposed that reactivation of these subsurface and more likely basement faults during late Alpine continental collision events in Cenozoic are responsible for deformation of the Zagros foreland structures. Epicentral location of recent earthquakes occurred along the faults demonstrate that they are neo-active.